Coating for fastenings



Patented Nov. 28, 1939 UNITED STATES PATENT OFFICE The American Steel and Wire Company New Jersey, a corporation of New Jersey No Drawing. Application March 26, 1938, Serial No. 198,323

2 Claims. (Cl. 85-10) It is both customary and desirable to treat or otherwise coat metal fastenings to render them non-toxic and sterile, or free from bacteria. This applies particularly to such fastenings which, when about to be used by the artisan, are often as a matter of convenience taken or placed in the mouth. For this purpose the fastenings are sometimes blued in a heat treating furnace. In other cases, various coatings have been applied such as cement coating. While some of these have been successful from one standpoint, they have been objectionable from another. A fastening that has been blued is thereby rendered sterile and bacteria-free but has been found to rust very easily when subjected for any length of time to moisture of the atmosphere, or from other sources. Other coatings, such as cement, while rendering the fastening rust-proof, have not been entirely satisfactory in that complaints are sometimes made that the fastenings are not entirely sterile and bacteria-free. A cement-coated fastening usually has a rough surface containing small depressions or pits therein where particles of dirt and bacteria very easily find lodgment. Such a fastening also has a comparatively poor appearance.

Thecoating of the present invention will not only render'the fastening non-toxic under all conditions of usage but will also afford better resistance to corrosion, and; due to the smooth surface and metallic opalescent luster which it will present, will give the fastening an eye ap peal and serviceability beyond that now obtained by the use of other coatings. At the same time it provides a fastening with a hard coating having greater holding power than ordinary nails.

The coating of the present invention will adhere firmly to the fastening under all conditions to which nails are ordinarily subjected, and is both water and moisture-proof, thus protecting its surface against rust and corrosion.

- Also, fastenings as heretofore coated sometimes become gummy or sticky, especially when stored in a warm or damp place, thus tending to stick together in the shipping packages. This is, of course, very undesirable. Nail machines are often used to drive fastenings and such coatings, when sticky, will prevent the fastenings from sliding easily and will, therefore, cause them to jam in the chutes of the machine.

The improved coating of my invention will not become gummy or sticky under conditions to which such nails are ordinarily subjected.

According to the present invention, the coating is composed of a lacquer which may consist upon its application to the fastener and with the addition of the solvent causes the coating to spread uniformly over the metal object to be coated, insuring that'it will flow into and cover up all pin holes. A thinner or solvent of the alcohol family is desirable as it serves to sterilize the coating and renders it non-toxic and bacteriafree. Butyl acetate is preferred as the solvent because it has a higher boiling point and, there- 20 fore, is less inflammable and hazardous to use than other alcohol solvents, such as ethyl acetate or acetone, and also because it has the added characteristic that it will flow better.

The pearl essence may be either pure or synthetic pearl essence. The pure quality is manufactured from a substance removed from the under side of fish scale, such as the scale from herring. Pearl essence consists of brilliant crystalloids and can be prepared not only from scales but from swimming bladders and other integuments of certain fish. Synthetic pearl essence is manufactured from a sodium solution and a substance obtained from various parts of certain fish, known by the trade name of H. P. scale. When pearl essence is added, it gives the coating material a metallic opalescent luster which cannot be otherwise obtained;

If it is desired to otherwise color the coating,

that can be done by simply adding a suitable 40 coloring material, preferably a dye to avoid density of coating. A preferred color is blue,.to simulate blued nails or tacks. Victoria blue may be used, which acts in [the same manner as methylene blue. A suitable pigment coloring may be used in the place of a dye, if desired. The coating can be made without any coloring material, in which case it will be clear and colorless and will give the metal fastening to which his applied a metallic opalescent luster of pearl essence. The metallic appearance will be caused by the color of the base metal and the opalescent luster by the, coating itself..

4 The coating, as described, will and should preferably have a thin consistency such as will permit an even and thorough distribution or spreading over the articles to be coated. It may be applied by spraying, dipping or, preferably, tumbling in a tumbling barrel; that is, a batch of nails and a small quantity of the coating material will be placed in a tumbling barrel and. tumbled together until allthe nails or articles are properly coated. The coating can be applied at ordinary room temperatures, ranging from degrees to degrees Fahrenheit, and thereafter may be air dried or baked in a heated oven or furnace if desired.

The coating will always remain dry regardless of the room temperature or at temperatures to which nails are ordinarily subjected.

Toxic and bacteria tests made on articles coated with the coating of this invention show that the coating is absolutely non-toxic and bacteria-free so that coated fastenings or objects may be safely carried in the mouths of the users, as is sometimes customary, without any injurious effects resulting from the coating.

The coating will not only resist corrosion due to atmospheric conditions but is capable of withstanding a 24 hour salt spray test without any signs of rust or corrosion.

The coating may be applied to either bright or previously blued fastenings, such as tacks or nails. By blued I mean fastenings that have been subjected to a high temperature in a furnace or oven until they have acquired a deep blue color. When the coating is applied to blued fastenings, it will give them an opalescent luster of adeeper blue than is obtained by similarly coating bright nails. Such fastenings will have both the base metal and the coating sterile and, therefore, will be doubly non-toxic and bacteria-free, the base metal having been rendered non-toxic by the bluing operation in the heat treating furnace, and the coating being inherently non-toxic and bacteria-free due to the non-toxicity of the substances of which it is composed. A blued fastening in and of itself gives the user the assurance that it is sterilized. The addition of the coating of this invention to the fastening will not detract from the non-toxic quality or color of the base metal obtained in the bluing operation, but will add to it by giving the fastening not only a deeper blue but a smooth, hard, glossy, opalescent surface, pleasing to both the eye and touch. vIt not only simulates but improves the appearance of the blued fastening. By adding a blue color such as a dye or pigment (preferably a dye) to the coating the color of the blued fastening will be enhanced still further, giving the fastening a beautiful deep blue opalescent luster, thereby in creasing its sales appeal.

While I have, in this application, specifically described an embodiment which my invention may assume in practice, it will be understood that this embodiment is merely for the purpose of illustration and description, and that various other forms may be devised. within the scope of the invention, as defined in the appended claims.

I claim:

l. A metal fastening constructed for frictional insertion in WOOCl' or the like, having a hard, smooth coating comprising a base selected from the group consisting of ethyl-cellulose, nitrocellulose or cellulose acetate and containing a resin effecting microscopic bonding of the coating to the fastening and to the material in which the latter is inserted, the coating being sterilized when applied to the fastening by a non-toxic alcohol solvent, the base and resin of the coating both being non-toxic and the fastening being fit for holding in the mouth of the user, the coating being free from any tendency to become gummy or sticky when the fastening is stored in warm or damp places.

2. A metal fastening constructed for frictional insertion in wood or the like, having a hard, smooth coating comprising a base selected from the group consisting of ethyl-cellulose, nitrocellulose or cellulose acetate and containing a resin cfiecting microscopic bonding of the coating to the fastening and to the material in which the latter is inserted, the coating being sterilized when applied to the fastening by a non-toxic alcohol solvent, the base and resin of the coating both being non-toxic and the fastening being fit for holding in the mouth of the user, the coating being free from any tendency to become gummy or sticky when the fastening is stored in warm or damp places, the fastening having a sterile, blued finish to which the coating is applied, the finish being obtained by heating the fastening in a furnace, the coating being completely waterproof and protecting the blued finish of the fastening from rusting.

JAMES R. THOMPSON. 

